HEALTH ENCYCLOPEDIA

Amnesia

What is amnesia?

Amnesia is a form of memory loss. Some people with amnesia
have difficulty forming new memories. Others can’t recall facts or past
experiences. People with amnesia usually retain knowledge of their own
identity, as well as motor skills.

Mild memory loss is a normal part of aging. Significant
memory loss, or the inability to form new memories, may indicate the presence
of an amnestic disorder.

Symptoms of amnesia

The primary symptom of amnesia is memory loss or inability
to form new memories. If you have amnesia, you will have difficulty recalling
facts, events, places, or specific details. The details can range from what you
ate this morning to the name of the current president. You will still retain
your motor skills, such as your ability to walk, as well as fluency in any
languages you speak.

There are multiple types of amnesia, including retrograde
amnesia, anterograde amnesia, and transient global amnesia.

Retrograde amnesia

When you have retrograde amnesia, you lose existing,
previously made memories. This type of amnesia tends to affect recently formed
memories first. Older memories, such as memories from childhood, are usually
affected more slowly. Diseases such as dementia cause gradual retrograde
amnesia.

Anterograde amnesia

When you have anterograde amnesia, you can’t form new
memories. This effect can be temporary. For example, you can experience it
during a blackout caused by too much alcohol. It can also be permanent. You can
experience it if the area of your brain known as your hippocampus is damaged.
Your hippocampus plays an important role in forming memories.

Transient global amnesia

Transient global amnesia (TGA) is a poorly understood
condition. If you develop it, you will experience confusion or agitation that
comes and goes repeatedly over the course of several hours. You may experience
memory loss in the hours before the attack, and you will probably have no
lasting memory of the experience. Scientists think that TGA occurs as the
result of seizure-like activity or a brief blockage of the blood vessels
supplying your brain. It occurs more frequently in middle-aged and older adults.

Infantile amnesia

Most people can’t remember the first three to five years of
life. This common phenomenon is called infantile or childhood amnesia.

Causes of amnesia

Dementia

A memory’s location in your brain is thought to depend on its
age. To lose old memories, you must have widespread brain deterioration. This
can be caused by Alzheimer’s disease or other forms of dementia. People with
dementia usually lose more recent memories first and keep older memories
longer.

Anoxia

A depletion of oxygen levels can also affect your entire
brain and lead to memory loss. This condition is called anoxia. If the anoxia
isn’t severe enough to cause brain damage, the memory loss can be temporary.

Damage to the hippocampus

Your hippocampus is a part of the brain and limbic system responsible
for memory. Its activities include forming memories, organizing memories, and
retrieving them when needed. Its cells are some of your brain’s most
energy-hungry and fragile. They’re most easily disrupted by anoxia and other
threats such toxins.

When your hippocampus is impaired, you will have difficulty
forming new memories. If your hippocampus is damaged in both halves of your
brain, you can develop complete anterograde amnesia.

Head injuries

Traumatic head injuries, as well as stroke, tumors, and
infections, can also cause damage to your brain. This damage can include
permanent memory problems. Concussions commonly disrupt memories of the hours,
days, or weeks before and after you were injured.

Alcohol use

Short-term alcohol use can cause blackout. This is a
temporary form of anterograde amnesia. Long-term alcoholism can cause
Wernicke-Korsakoff syndrome. If you develop this condition, you will have
difficulty forming new memories but may not be aware of it.

Trauma or stress

Severe trauma or stress can also cause dissociative amnesia.
With this condition, your mind rejects thoughts, feelings, or information that you’re
too overwhelmed to handle. A specific type of dissociative amnesia, called
dissociative fugue, can lead to unexpected traveling or wandering. It can also
lead to amnesia around the circumstances of traveling as well as forgetting
other details of your life.

Electroconvulsive therapy

If you receive electroconvulsive therapy for depression or
other conditions, you could experience retrograde amnesia of the weeks or
months before your treatment. You could also experience anterograde amnesia,
usually resolving within 2 weeks of the treatment.

How is amnesia diagnosed?

Amnesia can be diagnosed by your doctor or a neurologist.
They will start by asking questions about your memory loss, as well as other
symptoms you may have. They may ask a family member or caregiver to help with
their evaluation, since you may not be able to remember the answers to their
questions.

Your doctor may also use cognitive tests to check your
memory. They may also order other diagnostic tests. For example, they may use
an MRI or CT scan to check for signs of brain damage. They may use blood tests
to check for nutritional deficiencies, infections, or other issues. They may
also perform tests to check for seizures.

How is amnesia treated?

To treat amnesia, your doctor will focus on the underlying cause
of your condition.

Chemically induced amnesia, from alcohol for example, can be
resolved through detoxification. Once the drug is out of your system, your
memory problems will probably subside.

Amnesia from mild head trauma usually resolves without
treatment over time. Amnesia from severe head injury may not recede. However,
improvements usually occur within six to nine months.

Amnesia from dementia is often incurable. However, your
doctor may prescribe medications to support learning and memory.

If you have persistent memory loss, your doctor may recommend
occupational therapy. This type of therapy can help you learn new information
and memory skills for daily living. Your therapist can also teach you how to
use memory aids and techniques for organizing information to make it easier to
retrieve.

Preventing amnesia

The following healthy habits can lower your risk of
blackouts, head injuries, dementia, stroke, and other potential causes of
memory loss:

Avoid heavy use of alcohol or drugs.

Use protective headgear when you’re playing
sports that put you at high risk of concussion.

Stay mentally active throughout your life. For
instance, take classes, explore new places, read new books, and play mentally
challenging games.

Written by: Rachel BarclayMedically reviewed
on: May 11, 2016: University of Illinois-Chicago, College of Medicine

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.